Elevator door bridge



Jung 14, 1949. ALEXANDER 2,473,128

ELEVATOR DOOR BRIDGE Filed May 10, 1946 2 SheetLs-Sheat 2 Patented June 14., 1949 UNITED STATES P OFFICE 1 Claim.

It has been found necessary to provide means for bridgin the gap normally existing between an elevator car floor and a building floor at approximately the same level in order to permit the passage of heavy loaded trucks across the gap as well as to prevent accidents to individuals. Since the load which must be borne by these bridge mechanisms is, in many cases, substantial, the bridge must be of heavy construction and as a result difiiculty has been experienced in securing satisfactory ease of operation. Furthermore, such mechanisms have often been damaged due to misalignment of the elevator car floor with the building floor caused by either careless operation or by the shifting of the elevator as the load is added or withdrawn.

Among the objects of my invention is the provision of a simple and efiective elevator door bridge mechanism which can be inexpensively constructed, easily operated, and which incorporates means permitting the use of the bridge mechanism even While a substantial degree of misalignment exists between the elevator car floor and the building floor without damage to the bridge mechanism.

Generally speaking I attain outstanding ease of operation by providing a counterbalance which acts about a pivot point of the bridge, changing its effective moment about the pivot as the moment of the bridge about the same point changes, so that the bridge is always substantially counterbalanced. To minimize the possibility of injury to the bridge or its pivots, the bearing in which the bridge is journalled is vertically elongated to permit displacement of the pivot point upwardly against the counterbalance in instances where the bridge has been lowered into contact with the floor and the load is applied to the unsupported overhanging edge of the bridge. Thus instead of overloading the bridge and its bearings, the bridge is permitted to pivot about the edge of the floor bringing the unsupported edge downwardly until firm support is reached and permitting the pivot point to move upwardly in the elongated slot for a similar distance.

Reference is made to the drawings in which Figure 1 is a partially sectioned end view showing the general arrangement of parts with the bridge in raised position;

Figure 2 is a similar view showing the bridge in lowered position;

Figure 3 is a face view of a clip;

. Figure 4 is a side view of a chip;

Figure 5 is a horizontal section through the counterbalance and pivot assembly, the position of the parts when the bridge is in raised position being shown in full lines, and when in lowered position shown in dotted lines;

Figure 6 is a partially sectioned end view indicating the disposition of parts when the bridge is lowered into contact with a misaligned floor; and

. Figure 7 is a partially sectioned end view showing a modification of my device.

In compliance with R. S. 4888, I describe herein certain specific applications of my invention as, for example, the application of my invention to an elevator door in a building, but it is to be un derstood that the details as well as the form and disposition of parts herein described may be modified within the limits of the appended claims without departing from the scope of my invention.

To span the gap normally existing between the edge H of a building floor I2 and an elevator car floor I3, I provide an arched bridge M of sufficient width to span the gap. The bridge I4 is disposed in a doorway between door jambs l6 and will, in most instances, extend substantially across the space between the jambs l6. Slidably mounted upper and lower doors ll and H! are provided in the doorway, the lower door l8 carrying a clip generally designated Hi. The clip l9 may suitably comprise an upper leg 2| and a lower leg 22 connected by a Web 23. The upper leg 2| is provided with a laterally extending ear 24 and is somewhat narrower than the Web 23. The lower leg 22 may be attached to the upper portion of the lower door it as by welding and in such manner as to permit the upper leg 2! with the car 24 to project outwardly.

The bridge I4 is provided with slots in the path of the clip 19 of a width substantially equal to the upper leg 2| but narrower than the width of the upper leg with the car 24 so that as the door I8 is lowered, the ear 24 will engage the bridge I l adjacent the sides of the slot therein and move the bridge from a raised to a lowered position.

Opposed housings, generally designed 26, are

attached to each of the door jambs It as by bolts 21., Each housing 25 includes a flanged cover 28 and may include a backplate 29 when required by the structure of the door jamb. Vertically elongated openings 3| are formed in the cover 28 and inthe backplate 29, if one is employed, adjacent the level of the floor I2. Stub shafts 32 are journalled in the openings 3| and extend outwardly through the housingsZB a short distance. A counterbalance 33 extends laterally from each of the shafts 32 and is preferably formed integral with the shafts. The counterbalance is enclosed within the housing 26 by the cover 28 and may suitably taper outwardly from the shaft. If desired, a foot 34 may also be formed integral with the shaft 32 and extends laterally therefrom at an angle to the counterbalance to limit the travel of the counterbalance as the shaft 32 is rotated. r

A spring 36, preferably of the, cantilever type, is attached at one end to the housing 26, the free end of the spring extending inwardly therefrom into the path of the counterbalance Stand positioned to engage the face of the counterbalance only after the counterbalance has completed a. predetermined portion of its movement. The bridge [4 is rigidly attached to the shafts 32 by. clamps 3'! which include a relatively flat plate 38 and arms 39 extending upwardly from the plate M 38,,around the. shaft 32. The. plate 38. may be attached to the lower surface. of the bridge adjacenteach inner corner as by. rivets ll andextends under the shaft32 which may be provided with afiat surface to mate with the plate 38.

The arms 39 are, integral with the plate 33 and extend upwardly around the shaft 32 being drawn into frictional engagement therewith by bolts orrivets .42.

In normal operationthenfioor of the elevator car 53 maybe brought to the level of the building floor H andthe doors ll and l8 separated. As the lower door ls descendsthe clip it engages the bridge. I'd, drawing the bridge downwardly over the .upper end of thelower door 18 as seen in Figure 2, and bringing, the freeendof the bridge l4,.into contact with the elevator car floor 13. As the bridge I4 is lowered, the counter balance 33 is raised and in the latter portion of itstravelcomes incontact with the free endof i the spring 36, which is compressed or stressedby movement; of the counterbalance, reaching a. maximumat the point wherethebridge com pletes its. downward movement. The angle formed between the counterbalance and the bridge M isin excess of 90 in order that the center of gravity of the counterbalance will not pass the center of rotation of the. bridge even when the. bridge reaches itszlowest position. The

bridge l4l,is usually of substantial construction and appreciable weight since it must support relatively heavy loads. It is obvious that the, moment of the bridge about the shafts 32 will increase as the bridge is lowered, the increase being proportional to thechange in the cosine: of the angle between the bridge and thefioor H, The spring 36 is thereforeemployedto increase. the moment of the counterbalance asthe bridge approaches its lowered position and by properly selecting the spring 35, I am able to maintain the bridge in substantially balanced relationshipat any point between its terminal positions.

As the doorsare closed, the upper surface of the lower-doon l8 moves the bridge M upwardly,

the spring 36 assisting in moving the counter- 6 balance 33 downwardly. When the bridge is in raised position, the moment of the counterbalance is suflicientlygreat to maintain the free end of the bridge within the plane of the edge I l of the floor l2 but, inthe lowered position, the; combined weight of. the door l8 and the bridge. ['4 is sufiicient to maintain the bridge in lowered; position.

As. r ousl menbie s he b id ar h d, he ak ;thaarchlbe e pg ime ly.

midway between the two edges and generally parallel to the edge I I. One of the primary purposes of this arched construction is to permit the free edge of the bridge to contact an elevator floor [3 when the floor I3 is depressed below the level of the building floor l2 as shown in Figure 6. The misalignment of floors may either be caused by careless operation of the elevator, or by shifting of position of the elevator as the load thereon is increased or decreased.

I prefer to forrn the bridge) such manner that the distance from the peak of the arch to the shafts 32 is substantially equivalent to the distance from the shafts 32 to the edge ll so that theqbridge may assume the position illustrated in .Figure 6. It is, of course, possible that the elevator car floor l3 may be depressed below the point which can be reached by the free end of the bridge l4 and that while in this condition the free end could be subjected to a relatively heavyload. If this should occur, the bridge I4 will pivot about theedge of the floor H until it contacts the floor reams causing the shafts 32 to riSe in the elongated openings 3 I; This avoids a concentration ofstress on either the s hafts'32 or the. bearing edges of the openings. The truck can then be. .moved along the outer portion of the. bridge M until it passes the floor edge H at' which time the bridgewvill pivot about the edge" I! and assume its "normal position; It is, of

course, obvious that pwam mev mem' of the shafts 32 whe n thebijidge is in lowered position willbe resisted by the counterbalance and that in normal circumstances only the lower'porti'orl of the open for the shafts.

Springs other than the cantilever type may be employed either in place of or in conjunction wi h th nt rba aa 33'- F r, xam l i 43 may be formed rigidwith the shaft 32 extendlug-laterally therefrom adjacent the counterbal; ance 33. A rod itispivoted to the end of the arm d x ends .u v rd hiwsh' a v t i fifl 46 secured to the housing 26 or the, door jamb'jlB; above the shaft 32. A coil springfilis teles'c0ped' over the rod ,44 and maybe restrained position" by, a collar 48, the other end of the spring}? be; ing restrained by the pivoted guide "45. With this type of structure, the counterbalance 33 can, desired, be eliminatedsince the strength and re-' action characteristics l ef the spring may be se lectd to counterbalance the variable moment of the vbridge Mjin any position.

If the counterbalance 33 is employed, It may employ a springsomewhat shorter than the dis{ tancefbetween th'e collar ar na the pivoted guide when thebridge is in raised position so that the springwill not affept, the movement of the; parts. until,thecounterbalance has completed a; predeterminedportion of its travel. It will be; found that for, most, purposes an ordinary coil spring Will-be satisfactory. If the counterbalance, is employed, the, arm. 43. may .be 'eliminated and the rod .4 ll, pivoted; directly to the counterbaiance.

The foregoing detailed description has illus trated the application of my invention toeleva tor. doors inbuildings, but it is obvious that it is equally usableon an,elevator car and I therefo re do not to be understood, as limiting myself solely'to the use of my 'inveaegn inbu'ilding s.

I claim:

An elevator door bridge of the type, adaptcdto. be moved from araised .positiontoaloweredposition to span the gapbetweenan elevator car floor nd a. uild ng ear ia e ea lhiaee gs 3! will-serve as journal surfaces" along its inner margin to one of said floors and having a counterweight mounted on the opposite side of the hinge and projecting in a substantially horizontal direction above said one floor when the bridge is in raised position, thereby to effectively counterweight the bridge in such position, and spring means effective after the bridge has moved a given distance toward its lower position for yieldingly and increasingly resisting continued movement of the bridge to its lowered position, thereby to supplement and complement the decreasing effectiveness of the counterweight due to its shortened lever arm, and to spring-bias the bridge, when in lowered position, toward its raised position.

ELISHA E. ALEXANDER.

6 REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 1,152,012 Doren Aug. 31, 1915 1,529,122 Fischer Mar. 10, 1925 FOREIGN PATENTS Number Country Date 151,899 Switzerland 1932 

